1. Field of the Invention
The present invention relates to a color conversion processing apparatus and a color conversion processing method for converting input image signals, which are composed of image signals of process color plates and an image signal of a spot color plate, into output image signals of process color plates. The present invention also relates to a non-transitory storage medium that stores a program for performing such an image signal conversion.
2. Description of the Related Art
Heretofore, it has occasionally been practiced in the printing field to print a color image based on image signals of color plates in C, M, Y, K (hereinafter referred to as “process color plates”) and a color plate in a spot color (hereinafter referred to as a “spot color plate”). In this case, on condition a printing press that is unable to perform spot color printing is used to print the color image, then since the printing press is incompatible with the image signals, it is necessary to convert input image signals, which are made up of process color plates and a spot color plate, into output image signals made up of process color plates.
Generally, information concerning a spot color (hereinafter referred to as “spot color information”) is stored in association with the type of output profile that is suitable for a printing press. Therefore, since the output profile is updated in a case where an output device is calibrated, the output profile is changed from the inherent definition of the spot color, thereby resulting in a reduction in the reproduction accuracy of the spot color. In view of this problem, various processes have been proposed for achieving consistency between spot color information and output profiles.
Japanese Patent No. 4803048 discloses an apparatus, etc., in which, on condition it is judged that an output profile (color conversion table) is changed, the device-dependent value of a spot color also is changed based on the color conversion table.
Japanese Laid-Open Patent Publication No. 2010-011048 reveals an apparatus, which converts device-dependent color values on a reference medium into device-dependent color values on a new medium, using output profiles on the reference medium and the new medium.